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(Carrier Sense Multiple Access/Collision Avoidance) The transmission method used in Wi-Fi networks (IEEE 802.11). When a Wi-Fi device needs to transmit, it listens to the network (senses the carrier) and backs off a random amount of time (in microseconds). At the end of that period, as long as the network is idle, it transmits the frame. If the receiver gets the frame intact, it sends an acknowledgment (ACK) to the sender. If the sender does not get the ACK, it retransmits the frame. Also used in Apple's earlier, wired LocalTalk network, Wi-Fi is a data link protocol, and CSMA/CA is a MAC layer protocol (see MAC layer). See data link protocol, Wi-Fi and CSMA/CD.